Behavioural and physiological stress responses to environmental and human factors in different small mammal species: implications for their conservation

• Autores: Álvaro Navarro Castilla
• Directores de la Tesis: Isabel Barja Núñez (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2016
• Idioma: inglés
• Tribunal Calificador de la Tesis: Manuel B. Morales Prieto (presid.), Francisco Javier de Miguel (secret.), Federico Guillén-Salazar (voc.), Nuria Selva (voc.), Fernando Colmenares (voc.)
• Materias:
  • Ciencias de la vida
    • Biología animal (zoología)
      • Comportamiento animal
      • Comunicación animal
      • Fisiología animal
      • Mamíferos
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Wild animal populations are continuously subjected to periodic disturbances by environmental and anthropogenic causes. Thereby, in this doctoral thesis, we carried out different investigations to study the behavioural and physiological stress responses of several small mammal species to different environmental and human factors. Behavioral responses to predation risk, interspecific competition and human disturbances were analyzed by live trapping. For analyzing the correspondent physiological stress responses, fresh faeces of individuals captured were collected during each experimental situation and the quantification of faecal corticosterone metabolites (FCM) as indicator of the adrenal activity was performed in the laboratory by an enzyme immunoassay. Results showed that wood mice (Apodemus sylvaticus) individuals responded to predation risk situations by recognizing and avoiding their main known predators in the study areas (they did not respond to the faecal odour of an unknown one) and also avoiding increased moonlight. Besides, foraging activity and food intake vary in relation to the risky situations but no physiological stress response was found due to the increase in predation risk. In relation to the interspecific competition with wild ungulates, Algerian mice (Mus spretus) abundances were higher inside areas where ungulates were not present being habitat selection influenced by greater vegetation cover. Increased FCM levels inside areas without ungulates were due to the higher mice abundance whereas in the grazed areas depended on the higher soil compaction caused by ungulates. Finally, we studied whether human disturbances through agricultural practices and motorways affected small mammal populations. We found a smaller number of common voles (Microtus arvalis) inhabiting inside crops, additionally, individuals captured inside crops showed higher FCM concentrations. In relation to the motorway, wood mice living closer to the motorway showed the highest FCM levels. Based on these results, we can conclude that small mammals generally respond by altering their behaviour when facing daily environmental or human disturbances. However, only interspecific competition with ungulates and human disturbance evoked physiological stress reactions whereas predation risk factors did not evoke such responses, suggesting that maybe these cues are not enough reliable to experience physiological stress responses since prey species daily face the risk of predation and therefore such continuous responses could be costly and pathological for individuals. All the behavioural and physiological stress responses studied also depended on individual characteristics (e.g. sex, age and breeding condition) probably based on previous experience and the balance of costs-benefits in each particular situation at a given place and time. Since small mammals are good indicators of environmental impacts and they play an important role either as seed dispersers or as a major resource for many predators, hence, understanding how they cope with diverse difficulties could be crucial for developing effective management and conservation strategies in these and other free-ranging species.